Thanks a lot

I hope this is my last one for this series:
Watering holes - refers to Pubs or Bars or both

and thanks of course.

The police cars are standing near the pub and "waving the flag".
Does it refer to the red light that's working, or is it methphorical and they mean:
to make their presence felt, or so.
And my thanks.

In nature, I would say that a water hole contains water. At a watering hole, wild animals can find water to drink. Similarly, people can get a drink at a watering hole - a bar, a hotel or in England, a pub or public house.

I assume the police are looking for "drunken drivers", drivers who have drunk too much alcochol. Many countries set a maximum level of alcohol in the bloodstream for drivers. I don't know which country you refer to, or how the police would stop an approaching car. I think that it probably means making their presence known. Good luck!

By the way:
The police cars are standing near the pub just to keep things in order and it is in winnipeg Canada. I wondered if "waving the flag" means - with their lights on, or just - being present.

Thank you

Waving the flag (often "showing the flag") means making your presence felt by being visible. It's a bit like "gunboat diplomacy" where the prsence of the fleet is the message.